This invention relates to a drive axle device in a vehicle.
Conventional drive axle devices can be classified into semi-floating types, as shown in FIG. 1 and full-floating types, as shown in FIG. 2. In the semi-floating type drive axle device, as shown in FIG. 1, a differential gear unit 2 and disk brakes 3 are incorporated in a central housing 1, and planetary gear speed reducing units 6 are arranged at the brake sides of axle tubes 5 in which drive shafts 4 are incorporated. Each wheel 7 is supported by the axle tubes 5 through bearings 8 and 9 which are mounted directly on both ends of the drive shaft 4.
The semi-floating type drive axle device is disadvantageous in several respects. In order to overhaul either the gear unit 2, the brake 3, or the speed reducing unit 6, the axle tubes 5 and the drive shaft 4 must be removed from the vehicle body. Since the speed reducing unit 6 is disposed at the gear unit side of the drive shaft 4, the weight of the wheel 7 is imparted to the drive shaft 4, and accordingly it is necessary to increase the diameter of the drive shaft 4.
In the full-floating type drive axle device, as shown in FIG. 2, a planetary gear speed reducing unit 16 is arranged at the outer end of a drive shaft, a wheel mounting member 17a is rotatably supported through a pair of bearings 18 and 19 on the outer wall of the outer end portion of an axle tubes 15 in which the shaft 14 is incorporated, and a disk brake 13 is secured to the wheel mounting member 17a. By employment of the full-floating type drive axle device, the above-described drawbacks of the semi-floating type drive axle device can be substantially eliminated. However, the full-floating type drive axle device also has certain disadvantages. Since the planetary gear speed reducing unit 16 is arranged inside the wheel, the size of the wheel and the method of mounting the wheel are limited by the speed reducing unit 16.